It really depends on what you want to do with VCDS, if it is to only ever use it on a 2011
Ibiza, and you want to only ever read and clear logged faults, then someone selling VCDS Lite would suit your purpose, ie you buy a proper compatible interface and down load the older freeware version of VCDS which is VCDS Lite. If you want to be able to reprogram modules and perform basic setting for some replacement parts, then as a minimum you would need to buy a genuine VCDS HEX-USB+CAN that someone is selling on, but be aware that if you stay with VW Group cars, that listed used genuine version would run out of use as a complete tool on cars newer than 2016 roughly. So if that does not seem to be what you want to do and you aim to stay with VW Group cars in the future and would therefore end up with a newer than 2016 car sooner than later, then what you need is the VCDS HEX-V2 ??VIN.
As you will have worked out, this current version of VCDS comes with limited "full" use to either 3 or 10 cars with different VINs, the RossTech website explains the logic in that, so either as a DIYer you buy the 3VIN version or the 10VIN version, some basic tasks can be carried out on unlimited cars as outlined on the website.
I have owned this scan tool since maybe early 2002, first as VAG-COM which I traded in against VCDS when VW Group had changed things a lot, now I've traded my VCDS HEX-USB+CAN for a VCDS HEX-V2 10VIN as that version should suit my continued usage of this scan tool.
Edit:- out of staying away from copying scammers, stay away from things that don't sound exactly like VCDS as I'd doubt if they are ever updating it or providing any support, but I'd hope that you have read some of the earlier postings so know this, currently VCDS HEX-USB+CAN is running release 19.6.1 so anyone selling anything with an earlier release is a scammer.