[pupu144]

Is there a reason there are so many active versions? Is it because not all are compatible with all hardware?
Again with the passthru, what is this?
What about licenses and activations - any explanation for a newbie?

Because of legacy reasons:
S 6.2.0 / E 12.1 is last for 5054 (official support) and x86 OS.
S 7.2.1 / E 14.1 can work with 5054 with modified driver, but require x64 OS.

Anything newer require to use passthru driver for 5054, which brings some minor drawbacks in comparison with native driver support.

S 6.2.0 / S 7.2.1 / E 12.1 are freely available and doesn't require asking license keys from members (who usually set some minimal requirements for forum activity).

As for clones and what to buy - I believe I saw people recommending VNCI 6154 device on this forum..