You can provide an MD5 password during BGP peer-group create or update operations.
efa tenant service bgp peer-group create
--name <bgp-pg-name> --tenant <tenant-name>
--pg-name <device-ip:pg-name> --pg-asn <device-ip,pg-name:remote-asn>
--pg-bfd-enable <device-ip,pg-name:true|false>
--pg-md5-password <device-ip,pg-name:md5-password>
efa tenant service bgp peer-group update
--name <bgp-pg-name> --tenant <tenant-name>
--operation peer-group-add
--pg-name <device-ip:pg-name> --pg-asn <device-ip,pg-name:remote-asn>
--pg-bfd-enable <device-ip,pg-name:true|false>
--pg-md5-password <device-ip,pg-name:md5-password>
Example
efa tenant service bgp peer-group create
--name ten1bgppg1 --tenant ten1
--pg-name 10.20.246.15:pg1 --pg-asn 10.20.246.15,pg1:55001
--pg-bfd-enable 10.20.246.15,pg1:true
--pg-md5-password 10.20.246.15,pg1:password
--pg-name 10.20.246.16:pg1 --pg-asn 10.20.246.16,pg1:55001
--pg-bfd-enable 10.20.246.16,pg1:true
--pg-md5-password 10.20.246.16,pg1:password
efa tenant service bgp peer-group update
--name ten1bgppg1 --tenant ten1
--operation peer-group-add
--pg-name 10.20.246.15:pg2 --pg-asn 10.20.246.15,pg2:55002
--pg-bfd-enable 10.20.246.15,pg2:true
--pg-md5-password 10.20.246.15,pg2:password1
--pg-name 10.20.246.16:pg2 --pg-asn 10.20.246.16,pg2:55002
--pg-bfd-enable 10.20.246.16,pg2:true
--pg-md5-password 10.20.246.16,pg2:password1
efa tenant service bgp peer-group show --detail
============================================================================================
Name : ten1bgppg1
Tenant : ten1
State : bgp-pg-state-created
Peer Group
----------
Device IP : 10.20.246.15
Peer Group : pg1
Remote ASN : 55001
Next Hop Self : false
BFD Enabled : true
BFD Interval :
BFD Rx :
BFD Multiplier :
MD5 Password : $9$MCgKGaNt6OASX68/7TC6Lw==
Dev State : provisioned
App State : cfg-in-sync
Device IP : 10.20.246.15
Peer Group : pg2
Remote ASN : 55002
Next Hop Self : false
BFD Enabled : true
BFD Interval :
BFD Rx :
BFD Multiplier :
MD5 Password : $9$ufD04Gw+49ex4H8UtvifqA==
Dev State : provisioned
App State : cfg-in-sync
Device IP : 10.20.246.16
Peer Group : pg1
Remote ASN : 55001
Next Hop Self : false
BFD Enabled : true
BFD Interval :
BFD Rx :
BFD Multiplier :
MD5 Password : $9$MCgKGaNt6OASX68/7TC6Lw==
Dev State : provisioned
App State : cfg-in-sync
Device IP : 10.20.246.16
Peer Group : pg2
Remote ASN : 55002
Next Hop Self : false
BFD Enabled : true
BFD Interval :
BFD Rx :
BFD Multiplier :
MD5 Password : $9$ufD04Gw+49ex4H8UtvifqA==
Dev State : provisioned
App State : cfg-in-sync
============================================================================================
L1# show running-config router bgp router bgp local-as 4200000000 capability as4-enable fast-external-fallover neighbor pg1 peer-group neighbor pg1 remote-as 55001 neighbor pg1 password $9$MCgKGaNt6OASX68/7TC6Lw== neighbor pg1 bfd neighbor pg2 peer-group neighbor pg2 remote-as 55002 neighbor pg2 password $9$ufD04Gw+49ex4H8UtvifqA== neighbor pg2 bfd neighbor 10.20.20.4 remote-as 4200000000 neighbor 10.20.20.4 next-hop-self address-family ipv4 unicast network 172.31.254.46/32 network 172.31.254.123/32 maximum-paths 8 graceful-restart ! address-family ipv4 unicast vrf ten1vrf1 redistribute connected maximum-paths 8 ! address-family ipv6 unicast ! address-family ipv6 unicast vrf ten1vrf1 redistribute connected maximum-paths 8 ! address-family l2vpn evpn graceful-restart ! ! |
L2# show running-config router bgp router bgp local-as 4200000000 capability as4-enable fast-external-fallover neighbor pg1 peer-group neighbor pg1 remote-as 55001 neighbor pg1 password $9$MCgKGaNt6OASX68/7TC6Lw== neighbor pg1 bfd neighbor pg2 peer-group neighbor pg2 remote-as 55002 neighbor pg2 password $9$ufD04Gw+49ex4H8UtvifqA== neighbor pg2 bfd neighbor 10.20.20.5 remote-as 4200000000 neighbor 10.20.20.5 next-hop-self address-family ipv4 unicast network 172.31.254.46/32 network 172.31.254.176/32 maximum-paths 8 graceful-restart ! address-family ipv4 unicast vrf ten1vrf1 redistribute connected maximum-paths 8 ! address-family ipv6 unicast ! address-family ipv6 unicast vrf ten1vrf1 redistribute connected maximum-paths 8 ! address-family l2vpn evpn graceful-restart ! ! |

Note
The MD5 password cannot be set or unset on an existing BGP peer-group present within a peer-group instance. You need to remove the BGP peer-group from the BGP peer-group instance and then add back the BGP peer-group to the peer-group instance with the desired MD5 password configuration.