How to create ggmap with the new code overlaid with ggplot commands (geom_point, scale_fill_gradient)

Hello,

I was able to get the base map, but I was hoping to overlay the map with data at specific geographic coordinates. I also wanted to color the data points based on numerical values. I know the main github page provides some description on how to do this with the new code, but I'm not sure how much of what I originally had before the switch from Stamen to Stadia maps still works.

I am able to get the map with the following code:

GLGG <- c(left = -92.5, bottom = 41, right = -76, top = 49)

LGL <- get_stadiamap(GLGG, zoom = 6, scale = 2, maptype = "stamen_toner_background") %>% ggmap()

But when I run the following code:

GreatLakesSurfaceAlkalinity <- ggmap(LGL) +
theme_void() +
theme(plot.title = element_text(colour = "black", hjust=0.5),
panel.border = element_rect(colour = "black", fill=NA, size=1)) +
geom_point(data=GLDIC, aes(x=LONGITUDE, y=LATITUDE, fill=alkalinity), shape=21) +
scale_fill_gradient2(low="#e34234", mid="yellow", high="sky blue", space="Lab", guide="legend", aesthetics = "fill", midpoint = 1677, limits = c(800, 2400), breaks = c(800, 1200, 1600, 2000, 2400)) +
labs(title="Surface Mixed Layer")

I receive the following error:

Error in `ggmap()`:
! `ggmap::ggmap()` only plots objects of class `ggmap`
Run `rlang::last_trace()` to see where the error occurred.

It seems like I have to run the get_map() command, but I'm not sure how to reformat everything else.

I've attached the .csv file I used as my dataframe as "GLDIC". Any help would be appreciated. Sorry for all the questions!

Ben
[GLDIC.csv](https://github.com/dkahle/ggmap/files/14350142/GLDIC.csv)