Hello @stig0404,
You will be glad to know that if you register with the Dokan user role vendor, you will be able to sell a product also purchase a product. A vendor can also act as a customer and purchase from other vendors. However, the customer role is able to purchase only. So in case you need one user role with selling and buying ability, you can only use the vendor registration option and hide the ‘I am customer’ option from the registration page.
You are unable to make the change by default. You can hide the customer registration button.
/wp-content/plugins/dokan-lite/templates/global/seller-registration-form.php
Comment out line no: 60-63
<label class="radio">
<input type="radio" name="role" value="customer"<?php checked( $role, 'customer' ); ?>>
<?php esc_html_e( 'I am a customer', 'dokan-lite' ); ?>
</label>
Use // to comment out. Make the changes using a child theme so that you do not lose the changes during an update. It is recommended to use a child theme during such modification. The mentioned link can be useful to you for the purpose.
I hope this helps ??