arc42 is NOT part of the iSAQB Foundation curriculum.
Depending on trainers, it might be covered within iSAQB trainings.
If you are interested, you should check with your preferred training organisation in advance.
SysML (like UML) is a diagramming/modeling notation. Neither of them proposes any high-level structure for documentation.
arc42 proposes ONLY a high-level documentation/communicatin structure, and is notation agnostic: I've often used it with UML, and with informal box-and-lines diagrams.
In short: You need text + diagramming tools. Go as light as possible, start small (draw.io and Markdown/AsciiDoc). Use high-end modeling tools (like Enterprise Architect or ArchiMate only in larger teams and/or with formal documentation requirements (20+ devs). Have a look at docToolchain.
It's always the same: you get what you pay for. No company offers something for free: If it doesn't cost anything, you're the product:
They will use usage-data to optimize their commercial offerings, they will try out features in non-critical (aka: free) accounts first - so not to offend the paying customers.
In some cases (e.g. free web-mailers like gmx, Instagram, FB etc) the free versions are mainly vehicles for advertising.
Why should Oracle be any different? I cannot see their motivation to offer anything for free... they are *only* money-driven.