How can I transfer Mac data stored in the icloud to my new Inspiron desktop?

The new Mac must be signed in with same Apple ID and password on the same network with old Mac see the article Use iCloud File Sharing to share documents with other iCloud users - Apple Support

The applications like notes , calendars , photos , reminders , mail .... will also sync when the applications box of them are turned as on Turn iCloud features on or off - Apple Support

Set up iCloud on all your devices - Apple Support

Use an internet browser and log into www.icloud.com and manually download data or see the following: Set up iCloud on your Windows PC - Apple Support