btw: Im plotting my progress step by step with all problems i triped on.
So this is a howto by a noob for all other noobs :-)
so, first step done:
serial connector solderd and working ... under windows ...
now I have to get the connection with linux and I have to use a kubuntu-USB-Stick, i hope it works im also a linux-noob
btw. this USB-UART-Bridge works fine
I use this USB-UART-bridge:
in-circuit cp2104 uart bridge and its available on amazon, fairly ironic to buy it there

The drivers working well, so its a good match to ftdi i think.
I had to resolder the GND-wire, thats a typical problem with solderpoints on a big GND-Plate, but the EM-covers are also grounded, so its solderpoints are good alternatives.