Why can't I access my SSD drive on Mac Studio?

Select the folder in the finder.

choose GetInfo off the File menu

what are the permissions?

if you have Admin privileges, you can click to lock and unlock the permissions.

I find the easiest next step for me is to click the Plus sign, Add either Users = your own username or Group = Administrators Group, and then promote the newly added to Read&Write access.

here is an article discussing Permissions:

Change permissions for files, folders, or disks on Mac - Apple Support

You can also "Ignore Ownership" on the external volume by using the directions in the following Apple article:

If you don’t have permission to use files on a Mac disk - Apple Support

Whether you choose this option or @Grant's option depends on how you prefer to use the external drive. Most people will opt for "Ignore Ownership" since it is simpler especially if the drive is only used by one person.

each userid on each computer is unique. Giving a userid the same name on two computers does not mean that files owned by a userid on the other computer are available to a different user on a different computer, regardless of whether the accounts are named the same.

The Mac does not use those names internally -- they are for your convenience ... or in this case, your confusion.

what may have happened is that you created that drive as owned by one user on the old system, with no access for administrators.

to fix, connect it to the old system.

if you have Admin privileges, you can click to lock and unlock the permissions.

Then click the Plus sign, Add Group = Administrators Group, and then promote the newly added administrators group to Read&Write access.

-OR-

Connect it to the old system.

as HWtech suggests, unlock the lock and click Ignore owners.

Grant Bennet-Alder wrote:

oh, wait.

That's an EXFAT volume, not a MacOS volume. That drive does not use internal MacOS permissions.

You may need to use a Terminal command to fix that.

FYI, It also appears to be a Shared Folder in the screenshot since that checkbox is checked. I'm a little out of my depth for that option.

<< FYI, It also appears to be a Shared Folder in the screenshot since that checkbox is checked. I'm a little out of my depth for that option.>>

that just indicates it could be seen in File sharing from another computer, PROVIDED the permissions work.

I tried creating a temporary EXFAT drive with MBR partion and it gave me:

/dev/disk15 (external, physical):

   #:                       TYPE NAME                    SIZE       IDENTIFIER

   0:     FDisk_partition_scheme                        *15.7 GB    disk15

   1:               Windows_NTFS TexFAT                  15.7 GB    disk15s1

in Terminal, permissions were:

ls -ale

drwxrwxrwx   1 GrantH  staff  32768 Dec 31  1979 TexFAT

so it appears that such a drive is OWNED by the creator (not system or root) and group=staff

oh, wait.

That's an EXFAT volume, not a MacOS volume. That drive does not use internal MacOS permissions.

You may need to use a Terminal command to fix that.

yes it is simpler to reformat as a macOS format, such as macOS extended or APFS, BUT

reformatting is on the ERASE button, and everything on that drive will be ERASED.