@mykkalYou should be able to install extension. Extension provider would provide you with the installation instruction with the zipped code. You need to place the same in right folder.
For the setup wizard try updating your composer and see if that works. There can be tons of different reason for setup wizard is not working. However, you can deal with it later as well I guess.
- Tarandeep
Problem solved?Please give 'Kudos' and accept 'Answer as Solution'.