Let's try another way. Click on this link:
https://www.nxp.com/webapp/swlicensing/swlicensingIntermediate.sp
Select "Software accounts". Then click on the "NXP Software" in the list and then on "S32 Design Studio IDE".
This should bring you to this:

Is this working? If not, you can try different browser, maybe try to delete cookies... Not sure what's wrong on your side.
And as I explained above, there's no SDK for S32K1 for S32 Design Studio 3.6. And there won't be such SDK because it is already discontinued. It's replaced by RTD. Latest RTD 2.0.0 for S32K1 will work in S32DS 3.5. Next releases which are not available yet will be supported by S32DS 3.6.
Regards,
Lukas