I have recently bought a Connects2 Lexus USB Adapter with inputs for aux & SD card (CTALXUSB002).
It's supposed to be plug and play via the 5+7 pin CD changer's port. But my factory head unit does not have that port. Altough the car does have a CD-changer behind the glovebox.

Have any of you encountered the same problem? Is there any other aux adapters that will work on my car?
The car is a 1998 Lexus GS300 with navigation system, CD changer etc.

Link to the aux adapter I bought:
https://connects2.com/Product/ProductItem/CTALXUSB002

Based on the photos, the adaptor should fit in the bottom middle female connector on your radio assembly. Does it not?

Unfortunately, it does not.
They look similar but the number of pins doesn't match.

I see. If none of the plugs fit your unit, it must be the wrong adaptor. I haven't used the one you bought, but I do have a similar product installed in my 02 with Mark Levinson & navigation.

I have been searching on google for hours. All the adaptors I can find for 98-05 GS have this 5+7 pin connector. But the head unit in my car doesn't have that for some strange reason.
That's why I turned to ClubLexus as a last resort.

From the documentation for GROM's adaptors.
Perhaps such a thing is available from the company you used as well.