Adventure INTERFLIX - where, what, how, when?

Hello buddy!
Today my little Interflix adventure begins, and so that you know what is coming for you and me, I'll start from the beginning.
The thought of being at home for 6 weeks didn't let me sleep peacefully, so I had to come up with a solution. It was found faster than expected, because when I was just casually browsing the internet for ideas, I came across an offer from Flixbus. 'For 99€ throughout Europe' - that's approximately how I became aware of this ticket and it worked. INTERFLIX is the name of my ticket, which I purchased directly from Flixbus for 99€. This ticket consists of 5 vouchers, which are redeemed one by one. With this ticket, you can travel 5 routes, subject to the following conditions:
1. They must be direct connections
2. The routes must be traveled within 3 months, otherwise the vouchers expire
3. The return journey must not be identical to the outbound journey
So far, so good. Especially because of the first condition, you are not so free in terms of destinations, at least if you like me only want to travel with a small budget. After more or less thinking and planning, my destinations were already set. First, I want to go to Heidelberg because I really want to visit the city and a friend of mine studies there, so I have the opportunity to see him again after a long time. So, the first route is: Kassel - Heidelberg. A suitable connection was found in no time and the first voucher was redeemed. My bus leaves Kassel at 15:40 and I should be in Heidelberg by 20:30 as scheduled.
That's the only connection I have booked so far. But this has nothing to do with being clueless, because I deliberately didn't book anything else to have as much freedom as possible. Most likely, after one or two nights (spontaneity makes everything more exciting), I will travel from Heidelberg to Amsterdam, most likely continuing to Copenhagen, and then back to Germany, directly to the capital. From Berlin, I will already go back to Kassel. So, you could say that the routes are already determined, only the timeframe is still uncertain. However, it is also possible that I will completely abandon my plan along the way and come up with a new one. You never know ;-)

I'm getting on the bus now and I'll let you know when I arrive in Heidelberg -
See you soon, friend!