I'm a scientist at Twist.
The easiest way to access RPA is to buy a kit. It's quite involved to make the reactions from scratch so it's not trivial to DIY. There are lots of proteins, not all of which are commercially available individually (and certainly not economically).
The terms of supply are available online, but Section 6.4 is the relevant one, which is provided below.
6.4 The Buyer acknowledges and agrees that the Materials and Information are proprietary to the Company and may be covered by claims of patents or patent applications of the Company. The Goods are sold subject to the following restrictions:
(a) the Materials and Information are non-exclusively licensed to the Buyer solely for non-commercial internal research purposes.
(b) the Materials and Information must not be used for any commercial purposes or to provide services to any third party;
(c) the Buyer must not re-package or re-sell the Materials or Information;
(d) the Buyer acknowledges that the Materials are experimental in nature and may have properties that are not fully understood. Accordingly, the Buyer agrees not to use the Materials or derivatives thereof for any in vivo testing or for any clinical diagnostic purposes whatsoever for animals or humans;
(e) the Buyer shall use the Materials and Information strictly in
compliance with all applicable laws, regulations and guidelines.
The Company reserves all intellectual property rights in and to the
Material and Information, subject only to the license set forth above.
For terms and conditions see the License Card.
Here is a list of some academic publications by groups already using RPA.