can't buy a subscription on MacBook

What country?

Did you go to:

https://www.adobe.com/creativecloud/plans.html?sdid=KKQXH&mv=search&ef_id=EAIaIQobChMIs8Kh2IOI9wIVOh-tBh2KcAPeEAAYASAAEgLMMfD_BwE:G:s&s_kwcid=AL!3085!3!449365418602!e!!g!!creative%20cloud%20membership!151099240!109927014212&gclid=EAIaIQobChMIs8Kh2IOI9wIVOh-tBh2KcAPeEAAYASAAEgLMMfD_BwE

And select/pay for a plan?

Typically a Photography Plan.

After you have a subscription, then download and install the Adobe Creative Cloud Desktop App:

https://www.adobe.com/creativecloud/desktop-app.html

Then use that to install, authenticate, and activate the apps.

Well, subscriptions to Adobe products are done through Creative Cloud which you'll download along with Lightroom:

https://www.adobe.com/products/photoshop-lightroom.html?gclid=CjwKCAjw3cSSBhBGEiwAVII0Z7Paqu3ZETurQ8yxmJnb6NbZ517t9RQEwtOne-W3MGYroPF4p6eIThoCwwIQAvD_BwE&sdid=KKTGB&kw=semgeneric&ttsrccat=sem-ww-di-ps-brand&mv=search&ef_id=CjwKCAjw3cSSBhBGEiwAVII0Z7Paqu3ZETurQ8yxmJnb6NbZ517t9RQEwtOne-W3MGYroPF4p6eIThoCwwIQAvD_BwE:G:s&s_kwcid=AL!3085!3!442365420377!e!!g!!buy%20lightroom!1712238403!67643559340