At the moment, the option to log in to the Web Store using a Nintendo Account is not available. Please set an additional login provider (Google/Facebook/Apple account) to your Pikmin Bloom account in order to use the Web Store. Please see this support article for instructions.
What's the Pikmin Bloom Web Store?
The Pikmin Bloom Web Store is an online shop where you can purchase in-game coins and items at a great price. Purchases made on the web store will be immediately reflected to your account in the app.
Visit the web store and click on the price button for the item that you’d like to purchase. You will then be taken to the “Order Review” page.
Pikmin Bloom Web Store: https://store.pikminbloom.com
Click on the “Sign in to Purchase” button and sign in to your account.
※You must sign in with the same login credentials that you use for your Pikmin Bloom account. If you’re unsure about what credentials you’re using, you can review them by launching your Pikmin Bloom app and heading over to Settings > Account > Login Account.
※At the moment, it’s not possible to sign in to the web store using a Nintendo account. Please see here for details.
Select your payment method and complete the payment.