You don't need (and you can't) compile the deployable packages after installing them. They are dlls that the build created from source code.
Deployable packages don't contain source code. There's nothing to compile.
By the way here are instructions on how to handle third party models and binaries in your source control. You should really add the isv solutions to source control, too. Even if they are binaries only.
[View:https://docs.microsoft.com/en-us/dynamics365/unified-operations/dev-itpro/dev-tools/manage-runtime-packages]