Anyone can use this page! Even if you haven't used coinstructor.io service to create your ERC20 token - you can still put the ERC20 address here to check the parameters and add the token to Metamask.
We are working to enable Add To Uniswap functionality currently, and we plan to add more integrations for tokens - creating a Liquidity Provider Bootstrapping pool on Balancer, doing IBCO's, and many other things - stay tuned and subscribe to our social media to be the first to know. The functionality for tokens created with our service will be free.
Any Ethereum network supported by Metamask - you just need to switch to the needed network inside Metamask interface.
You need to have Metamask installed for the Management tools to work. You can download it from the official site.