https://www.dlsite.com/maniax/work/=/product_id/RJ049131.html

Dlsite has hidden several works from oversea buyers, and as result you can not access them even if you have bought them yourselves unless you have Japan IP.

As such, not recommend buying from Dlsite. If you still want to purchase, make sure to save them to your hardware/cloud or upload them so you can still access what you bought in the future.