Yes, you can sell what you make with Mini Skyline. There is no licence fee, no revenue share, no commercial tier, and no export cap.
What the policy asks for instead is a credit line in your listing and honest compliance with the licences of the map data your specific export actually used.
The three things to do before you sell
Check the commercial-use decision the export dialog states for that exact run, credit Mini Skyline in the product listing, and keep the licence bundle with any digital file you pass on.
What the permission does not cover
It covers the rights Mini Skyline owns in the model. It does not license raw source data for redistribution, and it does not clear architectural copyright, artwork, trademarks, or publicity rights in the place you depicted.
If it earns you money
Mini Skyline is a one-person project with no paywall. If a model you sold paid for itself, buying the developer a coffee is the whole business model.