Here's my 2cents to you:
At this point you have 2 options:
1. Go to †ђξ place before †ђξ D-day to confirm †ђξ authenticity of †ђξ place & try to do some research on them if you can, starting from a website address if they have one(which domain is †ђξ sender mail I'd carrying). Etc
2. & this is my candid opinion, no company should tell you to come corporately dressed for an aptitude test as you †ђξ applicant is expected to know what is considered appropriate otherwise what sort of employee are they looking at recruiting.
So, combine both nuggets together & see where it gets you. All †ђξ best!