I found a mistake in your template.The form used is the same used by XenForo user upgrades. Do you have issues with that too?
Template:
siropu_ads_manager_invoice_pay
Line 35:
<div class="js-paymentProviderReply-advertising{$invoice.invoice_id}"></div>
This div should not be inside the form.
Replace
HTML:
<xf:else />
<xf:formrow label="{{ phrase('choose_payment_method') }}" html="{{ phrase('siropu_ads_manager_no_payment_method_found') }}" />
</xf:if>
<div class="js-paymentProviderReply-advertising{$invoice.invoice_id}"></div>
</div>
<xf:if is="$hasPaymentProfiles">
<xf:submitrow icon="purchase" submit="{{ phrase('siropu_ads_manager_pay') }}" />
</xf:if>
</div>
</xf:form>
HTML:
<xf:else />
<xf:formrow label="{{ phrase('choose_payment_method') }}" html="{{ phrase('siropu_ads_manager_no_payment_method_found') }}" />
</xf:if>
</div>
<xf:if is="$hasPaymentProfiles">
<xf:submitrow icon="purchase" submit="{{ phrase('siropu_ads_manager_pay') }}" />
</xf:if>
</div>
</xf:form>
<div class="js-paymentProviderReply-advertising{$invoice.invoice_id}"></div>