I don't know that it is possible to make an online purchase for ANY edition. As far as I know, you have to work through the reseller assigned to your country. I know of some resellers who show products on an online shopping cart - but as far as I know, that just puts forward a purchase request that has to be resolved by humans. I hope I'm wrong ... many have wished for online purchase options for years. 🙂
Go to graphisoft.com which should open for the country you reside in and from the menu you can find the 'buy' option. This is supposed to be easier - but the old site listed all selling partners worldwide which made it a lot easier to help someone like you find the right contact. I can't find that map and list any longer.
One of the forum moderators
AC 26 USA and earlier • macOS Ventura 13.4, MacBook Pro M2 Max 12CPU/30GPU cores, 32GB