Every PCB is a unique design so the configuration might be different depending on your design. Please be very careful on selecting parameters on the JLCPCB ordering page. You do not want to make a trivial mistake and waste money when ordering your PCB.
Step 1: generate gerber files
https://jlcpcb.com/help/article/how-to-export-pcb-to-gerber-files-in-altium24
Please review the gerber files in an online gerber viewer (e.g. PCBWay Online Gerber Viewer)
Step 2: configure PCB manufacturing parameters
Once you upload the gerber files, you should reach this page shown below.
Make sure via is at least tented. Epoxy Filled & Capped is free if board layer >= 6
Change the stencil dimension to fit your board size, don’t use the default dimension as it adds shipping cost.
For other parameters, you can leave the same as shown in the screenshot above. However, there are some parameters we suggest you to consider:
Board Color (Black might be free under unknown conditions)
To change layer stackup, choose Yes for Impedance Control
Higher Inner/Outer Copper Weight increase PCB current carrying abilities
Remove Mark on PCB might be free under unknown conditions