Here's our advice about selecting a PMC, you may want to read it and apply it for better results in the future - coincidently, we do use tenant screening as an example of what owners should ask more questions about!

I am of the belief that the 150’ only applies to a JADU.  

Well that applies to new acquisitions as well, if that's your thought process. 

How can I apply for the process with the city?

It only applies to those who own more than 50 units, so if thats you I get why you're not happy, but I do believe this is a good thing for Americans.

By working with other real estate investors and building up your experience, you will definitely become a better investor and be able to apply your knowledge and experience to your own investing pursuits.

However, I haven't found a single video or article addressing how to apply it in Germany.Can you help me with this?

I’d like to see some of that goal setting applied to Sunbelt. 

You have a 1 bedroom so house hacking doesn't really work and most HOAs won't allow for short term rental and in some cases, arguably mid term rentals (I am starting to see no "transient" housing of any kind, so an argument could be made that this applies to mid-term). 

I am a small time STR operator in Wyoming, so my insight might not apply to larger areas, but I find that doing a theme for my STRs seems to get attention, The Rendezvous, The Cache, The Bunkhouse, The Eagle's Nest, The Cozy, etc.