Likely, for your situation, the answer is no. This deserves a little more detail.
To start, the process of using Apple Configurator to side load a retail device into ABM/ASM will only work on models with a T2 controller chip or higher. Thus, the 2014 and Apple Configurator will not work.
Now, despite the news above, there is a way. But, the stars must be aligned and you must have a relationship with the reseller who sold you the 2014, AND they must be able to assign devices to ABM via your Org ID (and their reseller ID must be in your ABM/ASM). Remember, ABM/ASM is all about chain of custody. If there is proof that your organization purchased the device, and you purchased the device from a DEP capable reseller, you can request that they submit the device for association. This is possible (we do it all the time and Apple has done it for EDU customers when they first establish ASM) but you must be able to prove ownership and have a willing and capable reseller partner. Since this unit was purchased 10 years ago, you may not be able to complete the chain. And if this device was purchased via a retail outlet (Apple Store but not talking to the Business Team, direct from Apple's website, Amazon, Best Buy, etc.), then there will be no way to prove chain of custody.
Finally, I need to ask. Why do you even still want the 2014? That unit is already 10 years old, it cannot run a supported OS, and at this point, your MDM may not even properly support it. It is likely better to find an M1 Air at a bargain basement price if you are looking for a test machine.
Hope this helps.
