Hi Allda.
The source text is confusing because I think the author has used the wrong word - "arbitrary" instead of "absolute". Whether this occurred because of a misunderstanding or a transcription error I cannot say. The term "arbitrary" is certainly not appropriate in this context. Moreover, the entire paragraph becomes perfectly clear if you substitute the word "absolute". "Absolute" contrasts with "relative" in a variety of fields.

Basically, the article is saying that for every medical encounter or procedure, there is a specific fee. The collection of these specific fees is called the "fee schedule". The fee schedule can be expressed in one of two ways - in absolute prices or in relative prices. "Absolute" prices can be expressed in dollars such as:
Appendectomy $2,500.00
Hysterectomy $3,000.00
Tonsillectomy $750.00.

Alternatively, the fee schedule can be expressed in "relative" values, for example:
1 unit = $750.00
Appendectomy 3.33 units
Hysterectomy 4.0 units
Tonsillectomy 1.0 unit

The advantage of relative units is that one can change the whole fee schedule just by changing the value of a unit to account for inflation or for fee increases over time, built into the contract.

As an aside, I once met a gynecologist who was complaining how the provincial fee schedule had not kept pace with inflation. In his mind, he kept his own relative fee schedule - how many hysterectomies he had to perform to buy a Chevrolet. Sadly, over a period of twenty years, the number had increased steadily! :-)

In answer to your question, the "arbitrary dollar amount", the "RVU" and the "payment amount" all refer to the same thing, the fee for a particular procedure.