In this case, you should do exactly what it says.
A Dynamics 365 environment can be configured to use an security group which "basically" acts as a filter on which users in your organization(AAD tenant) that should be imported as an users in the environment.
As it appears you've had access and lost it I would assume your it-admins at your organization have applied a security group to this specific d365 environment that you do not belong to, hence your user object in this environment will get disabled(see error code).
Please not that security group(AAD) and a security role(D365) are not the same thing.
So, contact your organizations it-team to verify and grant you membership to the assigned security group(assuming that you lost it unintentionally) which can be seen in the Powerplattform admin center.