Is it ok if I only provide the Unity Privacy Policy in the playstore or do I also need to create a button to opt in to the privacy policy if I want to use Unity ads?
Hello potatogamedevelopment,
If you want to use Unity Ads, you don’t need to do anything. Unity Ads has a built-in solution for that. Automatically present affected users with an opportunity to opt in to targeted advertising, with no implementation needed from the publisher. It should currently show to all users within the EU for GDPR and include those in California for the CCPA laws.
There’s legal information - Privacy consent and data APIs
Hope this answers your question. If you still have questions, please leave a comment. 
Have a good day.