Hi
Does it's a group part of a Azure AD / Active Directory or local group ?
If you can't use the console I suggest to run a script, in both case if local or ad/azure ad;
Something like; net localgroup GroupName [username] /add for local's group.
In powershell use the Add-ADGroupMember for AD.
In powershell use the Add-AzureADGroupMember for AzureAD.