Hey there @SH0DAN,
thanks for reaching out to the community !
This one, is going to be a bit long but don't give up just yet.
Error 18 prejects when older traces of the last Spotify installation or uninstall are left in your system and for some reason on your device's process.
As a first basic step please click Ctrl+Alt+Dlt and terminate each and every Spotify activity you see on ALL tabs.
Secondly, click on your win magnifing glass symbol (left bottom corner) and search the word "Run".
Then type "%appdate% in the search box. locate the Spotify folder, right click and press delete.
Restart you PC and try reinstalling the app.
Waiting to see how you did 😃
OneByBooRock Star 19
Help others find this answer and click "Accept as Solution".
If you appreciate my answer, maybe give me a Like.
Note: I'm not a Spotify employee.