BIMcloud Basic is compatible with Mojave from 2018.2.1.
For the issue:
1. Did you install more than one instance of BIMcloud Basic to the same machine? Maybe more than one are using the same ports.
2. Do you have any special characters in the path of the BIMcloud Server? Try to reconfigure it to the default path.
3. Does it help if you restart the BIMcloud Server service manually?
If you can't solve with one or another, please send me a private message to discuss further actions.
Customer Engagement Expert, Community Admin