Develope module

To be able to use Lightroom-Classic you would need a change of your subscription to the "Photography Plan"

'Lightroom' Plan > 'Photography' Plan

https://www.adobe.com/creativecloud/plans.html

You would want the 'reverse' of the advice in this Adobe link-

https://helpx.adobe.com/manage-account/using/change-plan.html

Be aware that the Photography Plan has limited (20GB) storage, unless you pay for added storage.

If you already have more than 20Gb in Cloud storage, I believe you have available time (60days??) to download your photos to your local hard-drives and Lightroom-Classic will do this automatically when 'Syncing' is switched on in Lr-Classic.

https://community.adobe.com/t5/lightroom-classic-discussions/bilder-von-lr-app-in-lrc-importieren/m-p/12187343#M237342

At a later date when all your photos have downloaded to Lr-Classic local folders, you could delete files from Cloud storage and then sync (unlimited) photos back to the Cloud from Lr-Classic Collections. These do not use any space of your 20Gb allocation but are available (as Proxy smart Previews) for editing & viewing with Lightroom on mobile devices.

SYNC FAQ