Open the system Settings app > Safari, then tap Extensions. Tap Blob, and enable the Allow Extension toggle. Optionally, enable Allow in Private Browsing.
For more details, see Apple’s Safari Extensions user guide.
No. Blob uses the native Safari Content Blocker API, which does not give Blob any information about websites you visit. Blob does not have access to website data, browsing history, or search history.
Blob only uses the native Content Blocker API, it is unfortuantely not able to block YouTube ads. Some other apps inject scripts into the YouTube webpage in order to block ads, but they require full access to webpages and cannot guarantee fully private browsing.
Refunds are process through Apple. See details here.