Can't create an Apple ID because the email is already in use.

Please click on the links and read the documents -->

Change your Apple ID - https://support.apple.com/HT202667 - "Follow these steps to change the email address that you use as your Apple ID." Plus special instructions if you want to change your Apple ID to an @icloud.com address.

"If you try to change your Apple ID to an @icloud.com email address that was created within the last 30 days, you will be asked to try again later.

If you see a message that the email address you want to use isn't available or is already in use, check that you or a family member aren't already using that email address with a different Apple ID. If a family member is using that email address, remove it from their account then try to use it."

Sign into your account and remove the address.

Apple ID - Manage  

Apple ID email addresses.   

Apple hasn’t published any guidance for using an address again. Normally, if your e-mail address was associated with an ID in any way, for example as a Notification email address or a Rescue e-mail address, then it can't be reused with another Apple ID for approximately one year. I have also seen posts that stated Apple told them there was a 30 day waiting period before the address could be used again.  You will need to get another e-mail address to use as your Apple ID or you can try waiting 30 days to see if that works.

From what I have gleaned from other posts on this forum you may have difficulties, particularly if this was a primary email address for an Apple ID. Apple may never let you re-use it since it is linked as a primary identifier for purchases made for a different account. I can't find my reference to this discussion but it was recent and a person posted Apple Support had told him he could never re-use his primary email as an ID for another Apple account. You will need to find a different email address to use for the company account so you can remove your iCloud one for personal use. However, I am not sure if Apple will then let you use that iCloud one as a primary email address as an Apple ID on a new account.

P.S. Most people who respond to posts on this forum are regular users like you. We don't know the inner workings of Apple and those who do know them wouldn't be able to post it here until it was public knowledge.