It's possible to assign free M365 licenses to users by adding them to a JumpCloud group. There's some backend work in Azure Active Directory (AAD), but a group can be created in JumpCloud and bound to AAD for licensing.
One catch: Microsoft requires Premium tier licensing.
Glad to be of service. It can only assign to a group, the group based licensing is handled exclusively in AzureA D. When we went to set this up AAD required specific licenses to be able to provision Group Based Licensing. The cheapest option was to add a Azure Active Directory Premium P1 license, which is $6/month. But we only added (2) of them, and simply having them in the account seemed to make the rest of the group based licensing work just fine.
Microsoft has some decent documentation about setting up Group Based Licensing, this KB is the most helpful IMO.
It's so simple to bind a user to a user group in JumpCloud and then see that group membership propagate to AzureAD/M365 and within a minute or two watch the license be assigned to a user. Just one step making user management a little bit easier.
Here is an excerpt showing what levels of licensing you need to have in your account to be able to use Group Based Licensing.
You must have one of the following licenses for every user who benefits from group-based licensing:
Paid or trial subscription for Azure AD Premium P1 and above
Paid or trial edition of Microsoft 365 Business Premium or Office 365 Enterprise E3 or Office 365 A3 or Office 365 GCC G3 or Office 365 E3 for GCCH or Office 365 E3 for DOD and above