22, College graduate, first big job, zero debt - Employer provides a match after 6 months, but doesn't provide Vanguard. Need advice on what/where to invest.

Hey all!

Semi-recent lurker here. r/pf has been an incredible resource for me for everything finance-related. As the title said, i've recently graduated college, and have paid off all student debt myself (thank you scholarships and work).

I'm 22, and have my first "big boy" job. 35k salary, all health (Medical, Dental, Vision) insurance premiums paid for. I'm creating my budget right now, but need some advice on where/how I should be investing. I've made sure to go through everything in the sidebar (ELI22 has been awesome and extremely relevant).

My employer matches 3% of a Simple IRA (Smaller business, no 401k) through American Century Investments. I have the option to either invest in what's called a One Choice Portfolio or build my own portfolio.

I've been pretty sold on Vanguard here..however Vanguard isn't an option (at least I'm not seeing it as an option provided by American Century Investments). I want to invest in an employer match (cause hey, free money), but also don't want to get caught down the line if I want to transfer funds but get charged a ton for a transfer.

Any advice here? Any experience with ACI? Advice with what to look for in ACI? Should I open a separate 401k anyway, or match my employer's percentage and open an individual Vanguard account? Any and all recommendations welcome. Trying to get a grip on this "adult life" thing; healthy budgeting, saving, spending..Any and all advice is welcome.