This is a bit annoying so it's a good idea to update the site and add Binance Network to the list and get the tokens recognized automatically.
To be fair, it is not explicitly mentioned that they 'support' BSC or other networks (at least on their GitHub page). Even though they can interact with BSC and other ETH forks, some of their code explicitly use ETH exchange/dex to fetch the name of the token. You can probably modify it and run it locally by modifying this part[1], though I'm not sure if there are other codes that need to be modified to make sure it will automatically fetch your BSC tokens. CMIIW.
[1]
https://github.com/Migratooor/migratooor/blob/main/utils/tokenLists.tsx