Gray KangaROOS high tops US size 5.5

They're a European size 36 which is like a US size 6. I didn't try these on before purchasing since 36s fit like 90% of the time, and lo and behold, they are too small. They definitely fit more like 5 or 5.5 so they're too tight for me. They were purchased in December 2021 in Barcelona, Spain with the tag still on, and unused. I don't have the original box though.