Hi Jovsap,
Welcome to Microsoft Q&A community forum!
To integrate Active Directory on prem on Azure you have several possibilities:
1 Create a dc in azure and via vpn synchronize it with the dc on prem.
2 replicate your active directory in azure AD, which leads to some limitations in terms of ou management and policies
3 Create an AD DS managed services in Azure, where domain controllers are managed by Microsoft where you can only perform user and group policy management actions.
However, this last solution provides for the replication that you will always have to go through Azure AD
Check this links for ref:
https://learn.microsoft.com/en-us/azure/architecture/reference-architectures/identity/
https://learn.microsoft.com/en-us/azure/architecture/example-scenario/identity/adds-extend-domain
https://thomasmitchell.net/how-to-extend-on-premises-active-directory-to-microsoft-azure/
Hope this helps
Cheers
Luca