For no frills resource management, something like Resource Guru works well. If you want all encompassing resource, task, portfolio type management then something like workfront.
The more complex / all encompassing the solution the more time it will take to set up and manage and the more chance it will get abandoned without a dedicated resource managing it..
https://resourceguruapp.com https://www.workfront.com
There are variants of both of these but they are fairly typical / representative of what's available. There's no perfect solution unfortunately.
Alternatively you could try something like Jira but whilst it would work well with the volume of projects, it does require some configuration to structure properly.