[Steam: General] I can't make an in-game purchase.

Troubleshooting

If you have the Steam overlay disabled or the setting is incorrectly enabled, you will not be able to make any in-game purchases, so make sure to check your overlay settings. It may be possible to improve the situation by trying the following.

【How to Enable the Steam Overlay】
・Settings on Steam
1. Launch Steam
2. Once Steam is open, access Settings


3. Click the In-game tab, and toggle on "Enable the Steam Overlay while in-game"


・Settings on Per-Game Basis
1.Navigate to the "Library", right-click the desired game, and select "Properties".


2.In the "General" tab of the "Properties" window, "Enable Steam Overlay while gaming" toggle.


For more information about the Steam Overlay, please check Here.
(This page on Valve's official Steam support site.)

・Check Image Resolution Settings
If the resolution setting is higher than your display's native resolution, the Steam Overlay may not display correctly.
If your resolution is set to “3840 x 2400”, try lowering it to “1920 x 1080”.

・Run Steam as Administrator
If Steam is not run with administrator privileges, some features, such as the overlay, may not function properly.
Please refer to the following FAQ for instructions on launching Steam with administrator privileges.
https://bnfaq.channel.or.jp/faq/detail/8335

Once you've tried the steps above, launch the game and press "Shift + Tab" on your keyboard to check if the Steam Overlay appears.

If the issue persists, please restart the Steam client.
To restart the Steam client, you need to completely exit Steam by right-clicking the Steam icon in the system tray (bottom-right corner of your screen) and selecting Exit Steam.
Please note that clicking the X button in the upper-right corner of the Steam window does not fully close the application.