I think the Philadelphia page on Limited Lodging is easier to understand than the Airbnb Philadelphia page
https://business.phila.gov/limited-lodging-regulations/
As I understand it, if you rent your own home for less than 90 days per year you don't need to do anything (besides reporting income). So if your occupancy rate is <25% you should be fine.
If you rent 90-180 days you need to pay $125 to the L&I department (by city hall) for a "use registration permit as a 'Limited Lodging Home'".
For 180+ days you need a "use registration permit for a 'Visitor Accommodations' use".
A rental license is not required.
A commercial activity license *is* required.
Airbnb pays the 8.5% occupancy tax for you.
Please correct me if I'm wrong on any of this!